Old NodeMCU 0.9 (ESP-12)

Bootloader

Flash NodeMCU firmware

download nodeMCU firmware and nodemcu_flasher32.exe (link on the bottom of this page or click here directly), in the flasher tool point the firmware file you downloaded, latest firmware can be found at [[1]].

connect USB cable and flash the firmware (If not auto, press the any of the button on board once then it will start)